Charles e



o. E. SCRIBNER. TELEPHONE EXGHANGB APPARATUS.

10,501,169 Patented Ju1y11,1893.

(No Model.)

MM? Y o NTTED STATES PATENT OEEICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE WESTERN ELECTRIC COMPANY, OF SAME PLACE.

TELEPHONE-EXCHANGE APPARATUS.

SPECIFICATION forming part of Letters Patent No. 501,169, datedpJ'uly 11, 1893.

Application filed -Inne 6, 1888. Serial No. 276,209. (No model.)

To all whom t may concern:

Be it known that I, CHARLES E. SCRIBNER, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Telephone-Exchange Appatus, (Case No. 58,) of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawro ing, forming a part of this speciication.

My invention relates to telephone exchange apparatus and circuits, and its objects are, first, to provide a means of signaling from each subscribers station to the central office r 5 and from the central office to each of the stations by the employment of a single source of current, and, second, to provide an arrangement of circuits, whereby a single battery at one point is made to supply different 2o subscribers transmitters over the same wire with which the signaling battery or generator is connected. The battery which furnishes current to several subscribers stations is connected into a metallic circuit while anz 5 other battery Whichis used for signaling the different subscribers is connected in a ground branch with the same metallic circuit. The transmitter of any subscriber, who is talking, is connected into this metallic circuit and any 3o subscriber, by simply taking down his telephone, automatically closes the signaling batter-y through his annunciator at the central oiiice. I provide in addition to the telephone switch, a key by which the subscriber may repeat the signal. The operator at the central office, by means of suitable switching apparatus, may send current from the same ignal battery over any individual telephone ine.

4o In the drawing are shown four subscribers lstations, l, 2, 3, 4, and the central office 5. At the central office is shown ordinary switchboard apparatus with annunciators, springjacks and means for connecting the different subscribers wires together. Individual telephone lines, l, 2, 3, 4, are shown connecting their respective subscribers stations with the central office. The circuit wire 5 connects from the central oflce to all of the subscrib- 5o ers stations in a complete metallic circuit, as

shown.

Each ofthe subscribers stations is provided with an'outfit consisting of the telephone c, bell b,- switch c and transmitter d. The circuit of the outfit may be traced as follows: First, when the telephone is on the hook, the main line connects with the lever c, thence through one of the contact points to bell b, thence to ground; second, when the telephone is removed from the hook, the line 6o is switched to the other contact point and thence through the receiver and transmitter coil to ground. Near the end of the switch lever is provided a spring contact e to which a connection is made by the switch lever during a portion of the time it is moving from one position to the other. This connection is but momentary and is always broken before the lever is arrested by coming into contact with either of its stops. Thespring contact 7o e is permanently connected at each station to the circuit Wire 5r At the central station, a battery 71, is shown with one pole grounded and the other pole connected to the circuit wire 5.

The circuit of the calling battery h at the moment contact is madebetween the lever c and spring c at any stationfor example, station Q-may be traced as follows: by the two branches of the metallic circuit 5 to the spring 8o ,c and thence to lever c and thence by line 2 to the switchboard thence through the annunciator to ground.

The drawing shows the telephone removed at station 2 with the shutter of said station 85 down. A plug is shown inserted at the springjack for the purpose of answering the callindicated by the fallen shutter.

The operator upon learning who is wanted inserts the other plug of the pair into the 9o springjack of the desired subscriber and signais him by depressing the key f connected to the said plug. Suppose the desired subscriber to be number 3, and the plug inserted in his springjack; now upon the depression of the key fthe circuit of the battery h may be traced to the wire 5, thence to said key f and thence bythe plug, springjaek and wire 3 to station 3and thence through the bell to ground, thus effecting the desired sig- Ioo nal. It will thus be seen that by the use of my improvement a common battery may be used to signal from the central office to the subscribers stations and from the different stations to the central office.

Introduced into the metallic circuit 5 is shown a battery 7o, the function of said battery being to supply the different subscribers transmitters withcurrent. This may be done in any well-known way. I am thus enabled to use the circuit into which is introduced this transmitter battery and the transmitters at the various stations, to convey current from the signaling battery L to the various stations. The metallic circuit may thus be used for two purposes in connection with the two batteries, one purpose being for signaling and the other purpose for supplying the transmitters with battery.

it each of the stations in addition to the spring contact c, I place a key g the depression of which serves to connect the line to the signaling circuit 5, and thus I provide an independent means for the subscriber to signal the central office, when,`for any reason, the first automatic signal is not answered.

In the cord between the two connecting plugs is provided a clearing-out annunciator Z through which the circuit of the signaling battery his completed when either of the connected subscribers replaces his telephone on the hook. The circuit thus formed may be traced from the battery 7i to the circuit wire 5 to the spring e and lever c, as before described, thence by line 2, springjack, plug, cord, key m and annunciator Z and thence through the plug to the other subscribers line and to ground. Thus at each motion of the switch lever at the subscribers station the circuit of the battery h is completed through the subscribers line tothe central station and to ground either through the subscribers individual annunciator-whereby a call is inade--or in case they are already connected through the clearing-out annunciator Z.

The transmitter and induction coil circuit as shown in this application, is described and claimed in an application, Serial No. 85,073, tiled February 14, 1883, upon which Letters Patent N o. 830,056 were granted November 10, 1885, for battery circuit for telephone exchanges.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- 1. The combination with the metallic circuit including several subscribers stations and a central station, of the transmitters at said stations connected therewith, two batteries, one battery being included in ,the metallic circuit for furnishing current to the transmitters and the primary coils of the induction coils of the transmitters connected therewith, and the battery being included in a wire branched from said metallic circuitto ground, the individual telephone lines of said stations, and switching apparatus; whereby signals lnay be sent over the metallic circuit, while, at the same time, the transmitters are supplied with battery, substantially as described.

2. The combination in a telephone exchange system of a metallic circuit extending to the different subscribers stations, a battery included -in the circuit of said metallic circuit, a ground branch from said metallic circuit at the central station including battery and individual telephone lines one to each subscrib-` ers station, said individual telephone lines each including a signal device at the central station, a transmitter and the primary coil of the induction coil thereof connected at each subscribers station with the metallic circuit and supplied with current from the battery included in said metallic circuit, and switching devices one at each subscribers station for branching the individual lines to the said metallic circuit, whereby transmitters may be supplied with battery and the signal devices operated, substantially as described.

3. In a telephone exchange the combination with telephone lines each connected through a switch and annunciator to ground at the central office and at their outer ends with a subscribers telephone outfit respectively, ofl

a metallic circuit, a branch circuit to ground containing battery h, and switching apparatus at the central oflice; whereby any subscriber may send current from said battery through his annunciator at the central office while the operator may send current from said battery through the bell of any subscriber wanted, substan tially as and for the purpose specified.

In witness whereof I hereunto subscribe my name this 23d day of May, A. D. 1888.

CHARLES E. SCRIBNER. Witnesses:

Clins. C. WooDwoR'rH, GEORGE P. BARTON. 

